Re: [opendds-main] Multicast RTPS_UDP between two networks

[Matthew T. <mat...@ad...>]

Thank you for your reply, Adam.

It's working now.
I found that I could not send any multicast traffic between the networks (testing with iperf2 as per: http://taosecurity.blogspot.com.au/2006/09/generating-multicast-traffic.html).

I reported this to my networking people and they resolved the matter after admitting that they had "neglected a piece of config".

Thanks again

---
Matthew Thyer
(08) 8313 9283
4.38 Ingkarni Wardli
Adelaide University


________________________________________
From: Adam Mitz [mi...@oc...]
Sent: Thursday, 1 September 2016 12:35 AM
To: ope...@li...
Subject: Re: [opendds-main] Multicast RTPS_UDP between two networks

Hi Matthew,

On 8/30/2016 3:55 AM, Matthew Thyer wrote:
> I have two hosts (VM & Pi) on different networks that need to communicate via a multicast group and I haven't been able to achieve this.
> I'm using OpenDDS 3.8 built with ACE+TAO 6.3.3, Oracle JDK 8u?(73+), OpenSSL 1.0.2h.
> Configurations are:
>
> OpenDDS VERSION:
>              3.8
>
> TAO VERSION:
>              6.3.3
>
> HOST MACHINE and OPERATING SYSTEM:
>          VM:
>              VMware ESXi 5.x, x86_64, CentOS 7.2
>          Pi:
>              Raspberry Pi v3 model B, ARMv7 32bit, Ubuntu MATE Linux 16.04.1
>
> COMPILER NAME AND VERSION (AND PATCHLEVEL):
>          VM:
>              gcc (GCC) 4.8.5 20150623 (Red Hat 4.8.5-4)
>          Pi:
>              gcc (Ubuntu/Linaro 5.3.1) 5.3.1 20160413
>
> CONTENTS OF $ACE_ROOT/ace/config.h:
> [...]
> CONTENTS OF $ACE_ROOT/include/makeinclude/platform_macros.GNU:
> [...]
> CONTENTS OF $ACE_ROOT/bin/MakeProjectCreator/config/default.features:
> [...]
> SYNOPSIS:
>              A Publisher and Subscriber will communicate fine when both are on same host (either VM or Pi) but I cannot get communication working between the hosts (on different networks) via multicast.
>
> DESCRIPTION:
>              Host "VM" has a FQDN which resolves to the IPv4 address on it's network interface.
>              Host "Pi" has an unqualified hostname which I've added to the /etc/hosts file so it resolves to the IPv4 address on it's network interface.
>              The hosts are on different networks and IT support say that they have configured the networks for IP Multicast and have provided me with a multicast group address of: 239.192.3.1
>              I understand that RTPS discovery will not work with the OpenDDS 3.8 native multicast transport so I'm attempting to use the RTPS_UDP transport and have attempted to configure the RTPS discovery accordingly.
>              I don't know how many hops are between the two networks so I have chosen a rather large TTL of 15.
>
>          The network configuration requires noting as:
>              Both machines have their network configured via DHCP but the configuration provided to Pi is such that:
>                  Pi receives an IP address only (no DNS or default router information).
>              Both machines are time synchronised (NTP) with Pi achieving this through the IPv4 address of the server.
>              I am able to ping and SSH between the machines.
>              IT support advises that no protocols are blocked between the networks.
>
>              I've read chapter 7 "Run-time Configuration" of the OpenDDS 3.8 Developer's Guide and created DCPS configuration files for each host as follows:
>
>          VM:
>              [common]
>              DCPSBit=0
>              DCPSDebugLevel=1
>              DCPSTransportDebugLevel=1
>              DCPSGlobalTransportConfig=rtps_config
>              DCPSDefaultDiscovery=rtpsDiscoveryConfig
>
>              [rtps_discovery/rtpsDiscoveryConfig]
>              InteropMulticastOverride=239.192.3.1
>              TTL=15
>              #MulticastInterface=10.33.230.1
>              MulticastInterface=eno16777984
>
>              [config/rtps_config]
>              transports=rtps_transport
>
>              [transport/rtps_transport]
>              transport_type=rtps_udp
>              multicast_group_address=239.192.3.1
>              ttl=15
>              local_address=10.33.230.1:
>
>          Pi:
>              [common]
>              DCPSBit=0
>              DCPSDebugLevel=1
>              DCPSTransportDebugLevel=1
>              DCPSGlobalTransportConfig=rtps_config
>              DCPSDefaultDiscovery=rtpsDiscoveryConfig
>
>              [rtps_discovery/rtpsDiscoveryConfig]
>              InteropMulticastOverride=239.192.3.1
>              TTL=15
>              #MulticastInterface=10.198.6.10
>              MulticastInterface=enxb827eb63fb61
>
>              [config/rtps_config]
>              transports=rtps_transport
>
>              [transport/rtps_transport]
>              transport_type=rtps_udp
>              multicast_group_address=239.192.3.1
>              ttl=15
>              local_address=10.198.6.10:
>
>
>              DEBUG OUTPUT omitted due to message length limitations!

The configuration looks reasonable to me.  Can you tell from logging or
wireshark if SPDP is working on 239.192.3.1?  If SPDP is working, SEDP
is the next step.  Are there any errors/warnings in the log? You can
send me the compressed log files or packet captures off-list or contact
me for file transfer info.

Another thing to try is adding SpdpSendAddrs=10.198.6.10:port to the
VM's discovery config where port=7400+250*domainId.  This will send the
SPDP messages direct unicast to the PI and see if that's enough to
bootstrap it.  That plus SedpMulticast=0 will result in an all-unicast
setup for discovery.  Once that's working you can revert those one by
one to try multicast.

Thanks,
Adam Mitz
Principal Software Engineer
Object Computing, Inc.

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